Install Services send mail from our Server/Computer

#sudo apt-get install ssmtp
and it required 2 more Apps:    * heirloom-mailx
                                           * mailutils
#We need to edit, ‘/etc/ssmtp/ssmtp.conf’:
root=vannak@gmail.com
mailhub=smtp.gmail.com:587
rewriteDomain=
hostname=vannak@gmail.com
UseSTARTTLS=YES
AuthUser=vannak@gmail.com
AuthPass=V@nN@K'sPassword
FromLineOverride=YES

#Then add each account that you want to be able to send mail from by editing,
 ‘/etc/ssmtp/revaliases‘:

root:vannak@gmail.com:smtp.gmail.com:587
localusername:vannak@gmail.com:smtp.gmail.com:587